The answer to 'when to replace circuit breaker' is that you should replace a circuit breaker when it is no longer functioning properly or has reached the end of its lifespan. Circuit breakers are designed to protect your home's electrical system by automatically shutting off the power when there is an electrical overload or short circuit. Over time, the internal components of a circuit breaker can wear out, causing it to fail to trip when needed or to trip unnecessarily.
Most circuit breakers have a lifespan of 20-30 years, but this can vary depending on factors such as the quality of the breaker, the electrical load it has been subjected to, and the environment in which it has been installed. Signs that it may be time to replace a circuit breaker include frequent tripping, difficulty resetting the breaker, and visible damage or wear to the breaker itself.